1 /* 2 * drivers/base/core.c - core driver model code (device registration, etc) 3 * 4 * Copyright (c) 2002-3 Patrick Mochel 5 * Copyright (c) 2002-3 Open Source Development Labs 6 * 7 * This file is released under the GPLv2 8 * 9 */ 10 11 #include <linux/config.h> 12 #include <linux/device.h> 13 #include <linux/err.h> 14 #include <linux/init.h> 15 #include <linux/module.h> 16 #include <linux/slab.h> 17 #include <linux/string.h> 18 19 #include <asm/semaphore.h> 20 21 #include "base.h" 22 #include "power/power.h" 23 24 int (*platform_notify)(struct device * dev) = NULL; 25 int (*platform_notify_remove)(struct device * dev) = NULL; 26 27 /* 28 * sysfs bindings for devices. 29 */ 30 31 #define to_dev(obj) container_of(obj, struct device, kobj) 32 #define to_dev_attr(_attr) container_of(_attr, struct device_attribute, attr) 33 34 extern struct attribute * dev_default_attrs[]; 35 36 static ssize_t 37 dev_attr_show(struct kobject * kobj, struct attribute * attr, char * buf) 38 { 39 struct device_attribute * dev_attr = to_dev_attr(attr); 40 struct device * dev = to_dev(kobj); 41 ssize_t ret = 0; 42 43 if (dev_attr->show) 44 ret = dev_attr->show(dev, buf); 45 return ret; 46 } 47 48 static ssize_t 49 dev_attr_store(struct kobject * kobj, struct attribute * attr, 50 const char * buf, size_t count) 51 { 52 struct device_attribute * dev_attr = to_dev_attr(attr); 53 struct device * dev = to_dev(kobj); 54 ssize_t ret = 0; 55 56 if (dev_attr->store) 57 ret = dev_attr->store(dev, buf, count); 58 return ret; 59 } 60 61 static struct sysfs_ops dev_sysfs_ops = { 62 .show = dev_attr_show, 63 .store = dev_attr_store, 64 }; 65 66 67 /** 68 * device_release - free device structure. 69 * @kobj: device's kobject. 70 * 71 * This is called once the reference count for the object 72 * reaches 0. We forward the call to the device's release 73 * method, which should handle actually freeing the structure. 74 */ 75 static void device_release(struct kobject * kobj) 76 { 77 struct device * dev = to_dev(kobj); 78 79 if (dev->release) 80 dev->release(dev); 81 else { 82 printk(KERN_ERR "Device '%s' does not have a release() function, " 83 "it is broken and must be fixed.\n", 84 dev->bus_id); 85 WARN_ON(1); 86 } 87 } 88 89 static struct kobj_type ktype_device = { 90 .release = device_release, 91 .sysfs_ops = &dev_sysfs_ops, 92 .default_attrs = dev_default_attrs, 93 }; 94 95 96 static int dev_hotplug_filter(struct kset *kset, struct kobject *kobj) 97 { 98 struct kobj_type *ktype = get_ktype(kobj); 99 100 if (ktype == &ktype_device) { 101 struct device *dev = to_dev(kobj); 102 if (dev->bus) 103 return 1; 104 } 105 return 0; 106 } 107 108 static char *dev_hotplug_name(struct kset *kset, struct kobject *kobj) 109 { 110 struct device *dev = to_dev(kobj); 111 112 return dev->bus->name; 113 } 114 115 static int dev_hotplug(struct kset *kset, struct kobject *kobj, char **envp, 116 int num_envp, char *buffer, int buffer_size) 117 { 118 struct device *dev = to_dev(kobj); 119 int i = 0; 120 int length = 0; 121 int retval = 0; 122 123 /* add bus name of physical device */ 124 if (dev->bus) 125 add_hotplug_env_var(envp, num_envp, &i, 126 buffer, buffer_size, &length, 127 "PHYSDEVBUS=%s", dev->bus->name); 128 129 /* add driver name of physical device */ 130 if (dev->driver) 131 add_hotplug_env_var(envp, num_envp, &i, 132 buffer, buffer_size, &length, 133 "PHYSDEVDRIVER=%s", dev->driver->name); 134 135 /* terminate, set to next free slot, shrink available space */ 136 envp[i] = NULL; 137 envp = &envp[i]; 138 num_envp -= i; 139 buffer = &buffer[length]; 140 buffer_size -= length; 141 142 if (dev->bus && dev->bus->hotplug) { 143 /* have the bus specific function add its stuff */ 144 retval = dev->bus->hotplug (dev, envp, num_envp, buffer, buffer_size); 145 if (retval) { 146 pr_debug ("%s - hotplug() returned %d\n", 147 __FUNCTION__, retval); 148 } 149 } 150 151 return retval; 152 } 153 154 static struct kset_hotplug_ops device_hotplug_ops = { 155 .filter = dev_hotplug_filter, 156 .name = dev_hotplug_name, 157 .hotplug = dev_hotplug, 158 }; 159 160 /** 161 * device_subsys - structure to be registered with kobject core. 162 */ 163 164 decl_subsys(devices, &ktype_device, &device_hotplug_ops); 165 166 167 /** 168 * device_create_file - create sysfs attribute file for device. 169 * @dev: device. 170 * @attr: device attribute descriptor. 171 */ 172 173 int device_create_file(struct device * dev, struct device_attribute * attr) 174 { 175 int error = 0; 176 if (get_device(dev)) { 177 error = sysfs_create_file(&dev->kobj, &attr->attr); 178 put_device(dev); 179 } 180 return error; 181 } 182 183 /** 184 * device_remove_file - remove sysfs attribute file. 185 * @dev: device. 186 * @attr: device attribute descriptor. 187 */ 188 189 void device_remove_file(struct device * dev, struct device_attribute * attr) 190 { 191 if (get_device(dev)) { 192 sysfs_remove_file(&dev->kobj, &attr->attr); 193 put_device(dev); 194 } 195 } 196 197 198 /** 199 * device_initialize - init device structure. 200 * @dev: device. 201 * 202 * This prepares the device for use by other layers, 203 * including adding it to the device hierarchy. 204 * It is the first half of device_register(), if called by 205 * that, though it can also be called separately, so one 206 * may use @dev's fields (e.g. the refcount). 207 */ 208 209 void device_initialize(struct device *dev) 210 { 211 kobj_set_kset_s(dev, devices_subsys); 212 kobject_init(&dev->kobj); 213 INIT_LIST_HEAD(&dev->node); 214 INIT_LIST_HEAD(&dev->children); 215 INIT_LIST_HEAD(&dev->driver_list); 216 INIT_LIST_HEAD(&dev->bus_list); 217 INIT_LIST_HEAD(&dev->dma_pools); 218 } 219 220 /** 221 * device_add - add device to device hierarchy. 222 * @dev: device. 223 * 224 * This is part 2 of device_register(), though may be called 225 * separately _iff_ device_initialize() has been called separately. 226 * 227 * This adds it to the kobject hierarchy via kobject_add(), adds it 228 * to the global and sibling lists for the device, then 229 * adds it to the other relevant subsystems of the driver model. 230 */ 231 int device_add(struct device *dev) 232 { 233 struct device *parent = NULL; 234 int error = -EINVAL; 235 236 dev = get_device(dev); 237 if (!dev || !strlen(dev->bus_id)) 238 goto Error; 239 240 parent = get_device(dev->parent); 241 242 pr_debug("DEV: registering device: ID = '%s'\n", dev->bus_id); 243 244 /* first, register with generic layer. */ 245 kobject_set_name(&dev->kobj, "%s", dev->bus_id); 246 if (parent) 247 dev->kobj.parent = &parent->kobj; 248 249 if ((error = kobject_add(&dev->kobj))) 250 goto Error; 251 if ((error = device_pm_add(dev))) 252 goto PMError; 253 if ((error = bus_add_device(dev))) 254 goto BusError; 255 down_write(&devices_subsys.rwsem); 256 if (parent) 257 list_add_tail(&dev->node, &parent->children); 258 up_write(&devices_subsys.rwsem); 259 260 /* notify platform of device entry */ 261 if (platform_notify) 262 platform_notify(dev); 263 264 kobject_hotplug(&dev->kobj, KOBJ_ADD); 265 Done: 266 put_device(dev); 267 return error; 268 BusError: 269 device_pm_remove(dev); 270 PMError: 271 kobject_del(&dev->kobj); 272 Error: 273 if (parent) 274 put_device(parent); 275 goto Done; 276 } 277 278 279 /** 280 * device_register - register a device with the system. 281 * @dev: pointer to the device structure 282 * 283 * This happens in two clean steps - initialize the device 284 * and add it to the system. The two steps can be called 285 * separately, but this is the easiest and most common. 286 * I.e. you should only call the two helpers separately if 287 * have a clearly defined need to use and refcount the device 288 * before it is added to the hierarchy. 289 */ 290 291 int device_register(struct device *dev) 292 { 293 device_initialize(dev); 294 return device_add(dev); 295 } 296 297 298 /** 299 * get_device - increment reference count for device. 300 * @dev: device. 301 * 302 * This simply forwards the call to kobject_get(), though 303 * we do take care to provide for the case that we get a NULL 304 * pointer passed in. 305 */ 306 307 struct device * get_device(struct device * dev) 308 { 309 return dev ? to_dev(kobject_get(&dev->kobj)) : NULL; 310 } 311 312 313 /** 314 * put_device - decrement reference count. 315 * @dev: device in question. 316 */ 317 void put_device(struct device * dev) 318 { 319 if (dev) 320 kobject_put(&dev->kobj); 321 } 322 323 324 /** 325 * device_del - delete device from system. 326 * @dev: device. 327 * 328 * This is the first part of the device unregistration 329 * sequence. This removes the device from the lists we control 330 * from here, has it removed from the other driver model 331 * subsystems it was added to in device_add(), and removes it 332 * from the kobject hierarchy. 333 * 334 * NOTE: this should be called manually _iff_ device_add() was 335 * also called manually. 336 */ 337 338 void device_del(struct device * dev) 339 { 340 struct device * parent = dev->parent; 341 342 down_write(&devices_subsys.rwsem); 343 if (parent) 344 list_del_init(&dev->node); 345 up_write(&devices_subsys.rwsem); 346 347 /* Notify the platform of the removal, in case they 348 * need to do anything... 349 */ 350 if (platform_notify_remove) 351 platform_notify_remove(dev); 352 bus_remove_device(dev); 353 device_pm_remove(dev); 354 kobject_hotplug(&dev->kobj, KOBJ_REMOVE); 355 kobject_del(&dev->kobj); 356 if (parent) 357 put_device(parent); 358 } 359 360 /** 361 * device_unregister - unregister device from system. 362 * @dev: device going away. 363 * 364 * We do this in two parts, like we do device_register(). First, 365 * we remove it from all the subsystems with device_del(), then 366 * we decrement the reference count via put_device(). If that 367 * is the final reference count, the device will be cleaned up 368 * via device_release() above. Otherwise, the structure will 369 * stick around until the final reference to the device is dropped. 370 */ 371 void device_unregister(struct device * dev) 372 { 373 pr_debug("DEV: Unregistering device. ID = '%s'\n", dev->bus_id); 374 device_del(dev); 375 put_device(dev); 376 } 377 378 379 /** 380 * device_for_each_child - device child iterator. 381 * @dev: parent struct device. 382 * @data: data for the callback. 383 * @fn: function to be called for each device. 384 * 385 * Iterate over @dev's child devices, and call @fn for each, 386 * passing it @data. 387 * 388 * We check the return of @fn each time. If it returns anything 389 * other than 0, we break out and return that value. 390 */ 391 int device_for_each_child(struct device * dev, void * data, 392 int (*fn)(struct device *, void *)) 393 { 394 struct device * child; 395 int error = 0; 396 397 down_read(&devices_subsys.rwsem); 398 list_for_each_entry(child, &dev->children, node) { 399 if((error = fn(child, data))) 400 break; 401 } 402 up_read(&devices_subsys.rwsem); 403 return error; 404 } 405 406 /** 407 * device_find - locate device on a bus by name. 408 * @name: name of the device. 409 * @bus: bus to scan for the device. 410 * 411 * Call kset_find_obj() to iterate over list of devices on 412 * a bus to find device by name. Return device if found. 413 * 414 * Note that kset_find_obj increments device's reference count. 415 */ 416 struct device *device_find(const char *name, struct bus_type *bus) 417 { 418 struct kobject *k = kset_find_obj(&bus->devices, name); 419 if (k) 420 return to_dev(k); 421 return NULL; 422 } 423 424 int __init devices_init(void) 425 { 426 return subsystem_register(&devices_subsys); 427 } 428 429 EXPORT_SYMBOL_GPL(device_for_each_child); 430 431 EXPORT_SYMBOL_GPL(device_initialize); 432 EXPORT_SYMBOL_GPL(device_add); 433 EXPORT_SYMBOL_GPL(device_register); 434 435 EXPORT_SYMBOL_GPL(device_del); 436 EXPORT_SYMBOL_GPL(device_unregister); 437 EXPORT_SYMBOL_GPL(get_device); 438 EXPORT_SYMBOL_GPL(put_device); 439 EXPORT_SYMBOL_GPL(device_find); 440 441 EXPORT_SYMBOL_GPL(device_create_file); 442 EXPORT_SYMBOL_GPL(device_remove_file); 443